How to start retinol or exfoliating acids without wrecking your skin

Retinol and exfoliating acids are the ingredients most likely to change how your skin looks, and the ones most likely to go wrong if you rush them. Our skin test now asks whether you have used them before, because the right first step depends on the answer. If you have not, this guide is for you.

What they actually do

Retinoids (retinol, retinal and the prescription ones) tell skin cells to renew faster. Over months that smooths texture, softens fine lines, keeps pores clearer and fades marks. Retinal works faster than retinol and is a little stronger.

AHAs such as glycolic and lactic acid dissolve the glue between dead cells on the surface, so skin looks brighter and smoother. Glycolic is the strongest of the common ones.

BHA, which is salicylic acid, dissolves in oil, so it works inside pores. It is the one for blackheads, clogged pores and oily, breakout-prone skin.

Azelaic acid is the gentle cousin. It hardly exfoliates, calms redness and fades post-acne marks, and most people tolerate it from day one, so the slow schedule below matters less for it.

Pick one to start

Choose by the problem, not by what is popular:

• Blackheads, oily T-zone, clogged pores: start with a BHA.
• Dullness, rough texture, a leftover tan: start with an AHA.
• Fine lines, uneven texture, marks that will not fade: start with a retinoid.

Only one. If you start two at once and your skin reacts, you will not know which one did it.

Beginner products, and what to wait for

The easiest way into BHA is a wash-off cleanser, because it is on your skin for under a minute. COSRX Salicylic Acid Daily Gentle Cleanser and CeraVe SA Smoothing Cleanser are both gentle enough to use daily once your skin is used to them. For a leave-on step, COSRX AHA/BHA Clarifying Treatment Toner is mild.

For AHA, The Ordinary Glycolic Acid 7% Exfoliating Toner, swept on with a cotton pad at night.

For a first retinoid, The Ordinary Retinol 0.2% in Squalane. The squalane base cushions it. After three months or so, if your skin is happy, Celimax The Vita-A Retinal Shot Tightening Booster is the next step up.

Leave the stronger mixes for later. Pads and toners that combine several acids, like Some By Mi AHA BHA PHA 30 Days Miracle Toner or Medicube Zero Pore Pad 2.0, are fine once a single acid sits well. The Ordinary AHA 30% + BHA 2% Peeling Solution is a ten-minute rinse-off peel, not a first product.

How often, week by week

1. Weeks one and two: two nights a week, with at least two nights in between.
2. Weeks three and four: three nights a week, if nothing has stung.
3. After that: every other night. Some people end up nightly with a retinoid; plenty never need to.

Use a pea-sized amount of retinoid for the whole face, on dry skin, after cleansing. Keep it off the eye corners, the edges of your nostrils and your lips. If your skin is dry or easily irritated, put moisturiser on first and the retinoid over it. It still works, just more gently.

Never on the same night

A retinoid and an exfoliating acid on the same night is the commonest way people damage their barrier. Alternate them. A week of both, once you are used to each, can look like this:

• Monday: retinoid.
• Tuesday: rest night, just cleanser and moisturiser.
• Wednesday: acid.
• Thursday: rest night.
• Friday: retinoid.
• Weekend: rest.

Rest nights are part of the plan, not a lapse. Skip scrubs, peel pads and clay masks on active nights too. A wash-off BHA cleanser in the morning is the one overlap most people tolerate, once both are familiar. For where each step sits in a full routine, see skincare routine order.

Sunscreen is not optional now

Acids and retinoids both make skin burn more easily, and in our sun that undoes their work fast: the tan, spots and texture you were treating come back. Every morning, two finger-lengths of SPF 50, even on a cloudy day or a day at a desk by a window. Our sunscreen guide helps you find one you will actually wear.

Purging or irritation?

Because these ingredients speed up how fast skin renews, clogs that were already forming can come to the surface sooner. That is purging. It looks like small bumps or whiteheads in the places you usually break out, it starts within the first few weeks, and it should be clearly better by about six weeks.

It is not purging, and you should stop, if:

• it stings or burns when you apply anything, even moisturiser;
• skin turns red, tight, shiny or starts peeling in sheets;
• bumps appear in places you never break out;
• it is no better after six to eight weeks.

That is irritation, and on its way to a damaged barrier. Stop every active, go back to cleanser, a ceramide cream and sunscreen, and follow our damaged barrier guide until your skin has gone two weeks without stinging. Then start again, more slowly.

Who should wait

If you are pregnant, trying to conceive or breastfeeding, leave retinoids out entirely and check any acid with your doctor. Our pregnancy-safe skincare guide explains what is usually considered fine. In the skin test, choose "Leave them out of my routine" and your routine will skip them.

If a doctor has prescribed tretinoin, adapalene or a strong acid, follow their schedule rather than this one. And if your skin is very reactive or you have rosacea, start with azelaic acid instead: Anua Azelaic Acid 10 Hyaluron Redness Soothing Serum or The Ordinary Azelaic Acid Suspension 10%.

See a dermatologist if your skin swells, blisters or cracks, or if acne is deep and painful: that needs more than a shop product. We sell everything named here, so weigh our picks with that in mind.